MongoCommandCursor
PHP Manual

MongoCommandCursor::getReadPreference

(PECL mongo >=1.6.0)

MongoCommandCursor::getReadPreference — Get the read preference for this command

说明

public array MongoCommandCursor::getReadPreference ( void )

参数

此函数没有参数。

返回值

This function returns an array describing the read preference. The array contains the values type for the string read preference mode (corresponding to the MongoClient constants), and tagsets containing a list of all tag set criteria. If no tag sets were specified, tagsets will not be present in the array.

范例

Example #1 MongoCommandCursor::getReadPreference() return value example

<?php

$m = new MongoClient('mongodb://rs1.example.com:27017', array('replicaSet' => 'myReplSetName'));
$collection = $m->selectCollection('test', 'people');

// If a MongoCommandCursor is constructed directly, it will inherit the read
// preference of the MongoClient instance passed to its constructor; however,
// MongoCollection::aggregateCursor() will have the MongoCommandCursor inherit
// the collection's read preference.
$collection->setReadPreference(MongoClient::RP_SECONDARY);

$cursor = $collection->aggregateCursor( [
    [ '$group' => [ '_id' => '$name', 'points' => [ '$sum' => '$points' ] ] ],
    [ '$sort' => [ 'points' => -1 ] ],
] );

var_dump($cursor->getReadPreference());

?>

以上例程会输出：

array(1) {
  ["type"]=>
  string(9) "secondary"
}

参见

MongoCommandCursor
PHP Manual